Thermal Conductivity Of Binary Mixtures Research Articles

Developing a two-grade model for the thermal conductivity of ionic liquids and their mixtures

Thermal conductivity (λ) is a crucial factor in the screening and design of ionic liquids (ILs) with desired thermal properties. Given the time consumption and computational inconvenience associated with structure-based models, a model grading strategy is proposed. This strategy aims to associate λ of ILs with their three reference properties separately in a two-grade model based on the kinetic theory and previous work. Subsequently, the model parameters are derived from the gathered database, and the prediction of λ is made with an average relative deviation (ARD) less than 5.78%. Further comparisons were conducted with the other three models, illustrating that our model exhibits high accuracy and is easily applicable, requiring only one of three reference properties. Finally, this model grading strategy is expanded to the determination of the thermal conductivity of binary mixtures (λm) of ILs without necessitating the individual λ values of each component. This approach accurately predicts the λm with an ARD less than 4.20%.

Thermal conductivity of ethylene glycol and water binary mixtures at evaluated temperature and pressure

Binary mixtures of ethylene glycol and water are widely used as working fluids in many areas, and the study of thermal conductivity is crucial in the determination of the heat transfer properties of related systems. In this paper, the thermal conductivity of these binary mixtures at a series of ethylene glycol concentrations (0 to 100 wt%) is measured experimentally using a transient hot-wire system at evaluated temperature and pressure range from 293–533 K and 0.1–15.0 MPa. Moreover, the experimental data are fitted into an equation as a function of temperature, pressure, and concentration, the average absolute deviation and maximum deviation between fitted values and experimental data are 0.29 % and 1.05 %, respectively, which shows that this equation describes our data very well. Furthermore, available experimental data in the literature are collected and the comparisons between literature data and our data are analyzed, our data agree well with most literature data. This work is expected to promote the use of binary mixtures of ethylene glycol and water as heat transfer working fluids in industries.

Thermal Conductivity of Binary Mixtures of 1,1,1,2-Tetrafluoroethane(R-134a), 2,3,3,3-Tetrafluoropropene (R-1234yf), and trans-1,3,3,3-Tetrafluoropropene (R-1234ze(E)) Refrigerants.

A total of 2160 thermal conductivity data points, measured using a transient hot-wire instrument, are reported for binary mixtures of R-134a, R-1234yf, and R-1234ze(E) refrigerants from 200 to 340 K to pressures of 12 MPa for mixtures containing R-1234yf and to 50 MPa for R-134a/1234ze(E) mixtures. Data are reported at compositions of approximately (0.33/0.67) mole fraction and (0.67/0.33) mole fraction for each binary mixture investigated. The estimated relative expanded uncertainty of the thermal conductivity measurements is less than 2%. The data are used to refit binary interaction parameters for the Extended Corresponding States (ECS) model implemented in REFPROP (version 10.0). Additionally, the data in this study are used to assess the performance of a generalized entropy scaling model for refrigerants. Finally, the strengths and weaknesses of the ECS and entropy scaling models are compared.

Liquid thermal conductivity of binary mixtures containing a diesel compound n-dodecane + biodiesel compounds: methyl caprate and ethyl caprate

Biodiesel which is comprising of Fatty Acid Methyl Esters (FAMEs) or Fatty Acid Ethyl Esters (FAEEs) mixtures, has attracted tremendous attention as a potential renewable and biodegradable fuel in internal combustion engines, because of their beneficial effects on pollution emission and engine performance. In this work, the liquid thermal conductivity of two binary mixtures containing a diesel compound n-dodecane + biodiesel compounds: methyl caprate and ethyl caprate was measured by means of transient hot-wire method at the teamperature range between 292 K and 362 K at atmospheric pressure. Based on the experimental data of two binary mixtures, the correction about three useful correlations which are available to calculate the liquid thermal conductivity of mixtures have been conducted.

Experimental Research on the Thermal Conductivity of Binary Mixtures with a Biodiesel Compound Ethyl Laurate + Three Alcohols (1-Propanol, 1-Butanol, and 1-Pentanol)

Biodiesel is recognized as a powerful substitute for diesel fuel. The alcohol can be blended with diesel or biodiesel for certain property improvements. In this research, the liquid thermal conduct...

Thermal performance of a binary carbonate molten eutectic salt for high-temperature energy storage applications

Molten carbonate eutectic salts are promising thermal storage and heat transfer fluid materials in solar thermal power plant with the feature of large specific heat capacity, wide operating temperature range and little corrosive. The high-temperature properties of molten carbonates should be determined accurately over the entire operating temperature for energy system design. In this paper, molecular dynamic simulation is used to study temperature and component dependence of microstructures and thermophysical properties of the binary carbonate molten salt. Negative linear temperature dependence of densities and thermal conductivities of binary mixtures of different components is confirmed with respect to the distances of ion clusters. Besides, positive linear temperature dependence of self-diffusion coefficient is also obtained. When temperature is constant, densities and thermal conductivities of binary mixtures are linearly related with components. Self-diffusion coefficients of CO32− firstly increase and then decrease with increasing mole fraction of Na2CO3. The temperature-thermophysical properties-composition correlation formulas are obtained, and the database of thermophysical properties of molten carbonate salts over the entire operating temperature is complemented, which will provide the essential data for heat transfer and storage system design, operation, and optimization in CSP.

Experimental studies on the thermal conductivity of methyl laurate component of biodiesel with three alcohols

Biodiesel has been considered as one of the feasible attempts to replace the fossil fuels. Alcohols always played a role as the additives to improve the certain properties of biodiesel. In this work, the liquid thermal conductivity of binary mixtures of methyl laurate usually the significant biodiesel component with three alcohols (1-propanol, 1-butanol and 1-pentanol) was measured with the temperature ranging within 287 K to 358 K at atmospheric pressure. The total standard uncertainty of the experimental results was estimated to be less than 2% (in the 0.68 confidence level) and the repeatability was better than ±0.5%. In addition, three useful correlations for estimating the thermal conductivity of mixtures have been fitted and optimized, and the maximum deviation of three correlations were less than 1.30%.

Research on the Thermo Physical Properties of Lauric Acid-Capric Acid Binary Mixture Phase Change Materials

Lauric acid(LA) and capric acid(CA) were mixed into binary mixture, whose melting temperature was predicted with Schroder’s equation and tested in step cooling curve method. Then latent heat was tested by DSC, and T-history method was used to test thermal conductivity of binary mixtures, heating and cooling characteristics were studied through expanded perlite(EP) adsorption of binary mixtures. Results show that Schroder’s equation can be used to predict melting temperature of fatty acid, and binary mixture prepared of 6:4 molar ratio has a high latent heat and its temperature is within a range that meets indoor comfort temperature. Thermal conductivity and the heating and cooling characteristics of the mixtures reveals that the thermal conductivity of fatty acid phase change material(PCM) is low, which restricts its latent heat release rate.

A knotted and interconnected skeleton structural model for predicting Young's modulus of binary phase polymer blends

A knotted and interconnected skeleton structural (KISS) model is proposed for predicting Young's modulus of polymer blends. The KISS model accounts for the structure variations of polymer blends using the percolation theory and emphasizes the structural symmetry of co-continuous polymer blends. It reduces to the Maxwell-Eucken models below the percolation threshold and a symmetric interconnected skeleton structure at an intermediate component volume fraction. The KISS model satisfactorily predicts the Young's modulus of polymer blends for the entire component volume fraction range. Due to mathematical analogy, the model might equally be applied to predictions of electrical and thermal conductivity of binary mixtures. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers

Prediction of transport properties of pure noble gases and some of their binary mixtures by ab initio calculations

The ab initio potentials of kinetic theory are used to calculate viscosity and thermal conductivity of pure helium-4, neon, argon, krypton, and xenon over the temperature range from 100 K to 5000 K at zero-density. The viscosity and thermal conductivity of binary mixtures of noble gases like helium–neon, helium–argon, neon–argon, argon–krypton, and argon–xenon are also obtained by ab initio calculations for temperature between 100 K and 5000 K at zero-density. The results of viscosity and thermal conductivity, both for pure noble gases and their binary mixtures are in good agreement with that of the literature. It is concluded that the ab initio calculations lead to a quantitative prediction of viscosity and thermal conductivity of pure noble gases and their binary mixtures.

Thermal Conductivities of Liquid Mixtures

This paper focuses on the empirical correlation of evaluated thermal conductivities of binary mixtures at different temperatures, the published correlations based on experimental thermal conductivities, the characterization properties for estimation at critical temperature, boiling point and critical volume for component 1, weight fraction for component 2, and thermal conductivity for components 1 and 2. Multiple regression analysis was used to develop the model. Detailed analysis shows that the proposed correlation fits the data from 61 experimental measurements with overall absolute error of 3.4%.

Vapor-Phase Thermal Conductivity of Binary Mixtures of Cyclopentane and R134a with R365mfc

The thermal conductivity of mixtures of R365mfc (1,1,1,3,3-pentafluorobutane), with R134a (1,1,1,2-tetrafluoroethane) and cyclopentane were measured using a transient hot-wire method, in the pressure range between 0.1013 and 0.7 MPa and temperatures between 311 and 413 K. The composition of the measured mixtures was 93.0% R365mfc + 7.0% R134a (kg/kg), 27.0% R365mfc + 73.0% R134a (kg/kg) and 62.8% R365mfc + 37.2% Cyclopentane (kg/kg). The Wassiljewa mixing rules modified by Mason and Saxena and the Extended Corresponding States Theory were used to correlate and to predict the experimental results obtained, with an average absolute deviation of 1.8 and 10%, respectively.

Transport properties of carbon dioxide+ethane and methane+ethane mixtures in the extended critical region

A practical representation for the transport coefficients of pure fluids and binary mixtures in and beyond the critical region of liquid-vapor equilibria is presented. The crossover expressions for the thermal conductivity, the binary diffusion coefficient, the thermal diffusion coefficient, and the thermal diffusion ratio incorporate scaling laws near the critical point and are transformed to regular background values far away from the critical point. In the limits of pure components, the crossover expression for the thermal conductivity of binary mixtures is transformed to the crossover expression for the thermal conductivity of pure fluids. For the calculation of the regular backgrounds transport properties of pure fluids, we use dense fluid contributions obtained from independently fitting pure fluid data and a dilute gas contribution from Chapman–Enskog theory. A comparison is made with thermal conductivity data for pure carbon dioxide, methane, ethane, and carbon dioxide+ethane and methane+ethane mixtures.

Synergistic Combinations of Thermally Conductive Fillers in Polymer Matrices

The use of thermally conductive adhesives to bond heat generating devices to heat sinks is an alternative production method for thermal management. It is of interest to be able to predict the thermal conductivity of an adhesive based on composition and rheology. A semi‐empirical model, for predicting the thermal conductivity of binary mixtures can be enhanced by taking into account filler interactions which affect the rheological profile of the system. Combinations of thermally conductive fillers, which can form structure within the polymer matrix, are shown to offer higher thermal conductivity. The Lewis and Nielsen model, can be used to predict the thermal conductivity of structured matrices by relating the rheology of the system to the effective aspect ratio of the filler particle.

The thermal conductivity of binary mixtures of liquid R22 with R142b and R152a at low temperatures

The paper presents the thermal conductivity of mixtures of liquid refrigerants, The group of systems studied consists of two binary mixtures of R22/R142b and R22/R152a. The measurements have been carried out in the temperature range 160–300 K for pressures From 0.2 to 8.0 MPa in a transient coaxial-cylinder instrument. The uncertainty of the thermal conductivity data is estimated to be ±2%. The experimental method and apparatus were validated by using the measurements of refrigerant R22. The results presented have been used to develop a correlation for the description of the thermal conductivity of refrigerants.

A prediction method for thermal conductivity of alternative refrigerants in the liquid phase

A prediction method for the thermal conductivity of halocarbon refrigerants in the saturated liquid state in the reduced temperature range 0.3 to well above 0.9 is presented in this paper. The aim of the method is to present a very simple calculation of the transport property useful for engineering purposes. The method determines thermal conductivity as a sole function of the reduced temperature and requires the knowledge of a parameter dependent upon easily available physical constants characteristic of each compound. The method is validated against experimental data available in the literature, giving average absolute deviations which are usually less than 5%, with maximum absolute deviations generally less than 10%. An extension of the method to estimate thermal conductivity of binary mixtures is also presented, along with a comparison with the few experimental data available in the literature.

Asymptotic behavior of the thermal conductivity of a binary fluid near the plait point

Abstract An extended asymptotic theory for the thermal conductivity of binary mixtures near plait points and critical mixing points is presented. The essential improvement upon previous theories is caused by the systematic inclusion of the background contribution in the kinetic coefficients. New experimental data obtained for carbon dioxide-ethane mixtures close to the line of liquid-vapor critical points are consistent with the extended asymptotic theory.

Composition dependence of the thermal conductivity of low-density polyatomic gas mixtures

We present a predictive scheme for the composition dependence of the thermal conductivity of mixtures containing polyatomic gases at zero density. This supplements earlier work which developed a method to interpolate for the composition dependence of dense gas mixtures, as well as an earlier procedure to calculate the thermal conductivity of mixtures of monatomic gases. In all cases, the algorithm makes use of accurately measured values of the thermal conductivity of pure gases and is validated with the aid of almost equal accurately measured values of selected binary mixtures. Such accurate data have been obtained mostly in transient hot-wire instruments. The formulae proposed for the calculations use the Monchick-Pereira-Mason kinetic-theory analysis as a starting point but contain a number of detailed improvements. The present algorithm is tested by comparison with measurements on 22 mixtures, which show absolute average deviations from the predictions ranging from 0.7 to 2.7%, with one unexplained case, that of CF4-He mixtures, which show deviations reaching as much as 7%. We estimate that the algorithm predicts the zerodensity thermal conductivity of binary mixtures, containing at least one polyatomic component, with a probable error in the order of 2%.

Absolute measurement of the thermal conductivity of alcohol + n-hexane mixtures

New absolute measurements, by the transient hot-wire technique, of the thermal conductivity of binary mixtures of n-hexane with methanol, ethanol, and hexanol are presented. The temperature range examined was 295–345 K and the pressure atmospheric. The concentrations studied were 75% by weight of methanol and 25, 50, and 75% by weight of ethanol and hexanol. The overall uncertainty in the reported thermal conductivity data is estimated to be ±0.5%, an estimate confirmed by the measurement of the thermal conductivity of water. A recently extended semiempirical scheme for the prediction of the thermal conductivity of mixtures from the pure components is used to correlate and predict the thermal conductivity of these mixtures, as a function of both composition and temperature.

Thermal conductivity of organic liquid binary mixtures: Measurements and prediction method

A correlation presented in previous papers for the prediction of organic liquid thermal conductivity, λ, is generalized in order to estimate the thermal conductivity of the binary mixtures of organic liquids. The proposed equation contains the reduced temperature, the molar fractions, and two factors characteristic of the components. The comparison between predicted and experimental A values is developed at atmospheric pressure, taking into account data present in the literature and experimental values obtained at the Department of Energy of Ancona University, using the steady-state hot-wire method. Fifty binary mixtures are considered (28 of them are investigated by the authors at 25 and 50°C), and the mean general deviation between predicted and experimental thermal conductivity values (621 data points) is 2.5%.